Hi folks,
My 3kw Elcon charger has continued to work since I replaced a blown capacitor in it. It was a new unit that I had trouble with Elcon not doing a repair on (long story). Anyway, I ended up with the thing in a bricked state. I dug around in the potting where it was all blacked and found the blown cap. It works well now (20amps) and does all the right things except that it cuts out after exactly 1 hour. I can restart it immediately by toggling the “Charge sense” on the BMS. It does everything else correctly.
It is not hot, it charges at 20A and it cuts out when the BMS says to. I never get to the full pack V because of imbalance in the cells, which I am working on. In every other sense it works fine.
The only clue I have is that someone suggested that the RRGG blinks on the indicator when the AC power comes on means that it has a comms error. It is only using a “Charge Enable”, not the CAN comms though so I don’t know what is going on.
Does anyone have any ideas?

It works well now (20amps) and does all the right things except that it cuts out after exactly 1 hour.

Weird. There is nothing in the charger firmware that happens after exactly one hour. There is an accumulated amp-hours figure, but that is calculated every minute

I can restart it immediately by toggling the “Charge sense” on the BMS.

I'm not familiar with that. What brand is the BMS, and can you briefly describe that the "charge sense" switch (?) does?

The only clue I have is that someone suggested that the RRGG blinks on the indicator when the AC power comes on means that it has a comms error.

On startup, a non-CAN model (which is what you presumably must have) will blink n reds followed by a green (all of these 500 ms on, 500 ms off, so one flash per second). The number of red flashes, n, is the user selected "curve", which is really just a selection of up to ten combinations of (battery capacities and number of cells). So you have user selection 2.

The last green doesn't make sense. Most error codes start with RG or GR (no gaps between the initial and following colours). However, early chargers had a bug, corrected in later versions, where the "charger overheated" error would display as "G _ _ _ _ _ _ _" instead of the intended "G R _ _ _ _ _ _" (the _ indicates one second of black, i.e. both red and green LEDs off). But then it would repeat every 8 seconds (so you would see a green flash for 1 second, then 7 seconds of no LED). "Communications error" is supposed to be R G R G R G R _ .

It's poorly documented that getting stuck in state zero (not charging, usually due to battery not being detected, or the enable signal being low) results in R _ G _ R _ G _ ... (i.e. alternating reds and greens, with black between both).

It is only using a “Charge Enable”, not the CAN comms though so I don’t know what is going on.

It must be a non-CAN model then. CAN models have completely different firmware, with no charging smarts at all. They rely completely on the battery management system or other system telling them what voltage and current to target. They don't use the enable input at all.

So my guess is that when the charger stops after an hour, it's because the BMS told it to stop, by setting the enable input low. Can you monitor the voltage on the enable input (pin 1 of the 7-pin round connector) with respect to the "ground" (WARNING: this is at battery negative potential!) (pin 2 of the 7-pin round connector)? Enable is often a black wire, with "ground" being green. There is commonly a third wire, red, with is about 11-13 V positive with respect to "ground" (this 12 V supply is connected to pin 3 of the 7-pin round connector).

Another thing you could try is to connect pins 1 and 3 of the 7-pin round connector (usually black and red respectively). This will pull the enable input to 12 V, which will enable the charger. But you need to do this safely; you might damage the BMS if you short the wires when the BMS is running, and both wires are at pack negative, so there is risk of electric shock and severe damage to the charger if you get it wrong. If the charger resumes charging at that point, it would certainly prove that the problem is in the BMS and not the charger.

Perhaps there is a cell that is going over-voltage after an hour of charging. When the BMS detects this, it disables the charger. Some chargers allow proportional charging via the enable input (e.g. 3.5 V enable to ground means 50% charge current), and some BMS are able to use this. If the charger and BMS support this mode, then you might be able to nurse your battery towards full charge, and have some balancing happen (if the BMS does top balancing). You mentioned unbalance in your battery, so it might be that when this is addressed, the problem will resolve.

[ Edit: clarified what is connected to pin 3 of the 7-pinm round connector. ]

Learning how to patch and repair PIP-4048 inverter-chargers and Elcon chargers.

Thanks for the quick response coulomb.
Just to be certain we are talking about the same unit, my charger is the Elcon 3.3kW UHF charger (solid Al box with a fan on it). It is full of white potting. My BMS is a ZEVA which monitors every cell and does the balancing. I also have the original BMS modules from EV Power still on each cell although they are not actively interfacing with the charger. My pack is 7 years old and thus has a mix of old and new cells (out of 45 cells there are 8 newer ones). The BMS is working properly as it does stop the charger when one cell is full. Ian H (ZEVA) has no ideas on the 1 hour / 20Ah cutout either. "Charge sense" just tells the BMS that the 240V cable is connected (it is a simple magnetic switch on the plug cover).

I am quite certain that the BMS has not told the Charger to stop. I even took it out of the picture and simply shorted the charger "Enable" wires together. Same result...20 Ah...stop (20 Ah is 1 hour at 20 A).

When I first installed the charger it charged the pack just once and then stopped working. No lights, no sign of life at all. After months of trouble with Elcon and Chinese customs, the unit was returned to me in the bricked state. As I am a tinkerer, before I dropped it in the bin I took the lid off and dug around the potting where it was black from an obvious "smoke escape" event. I replaced an obviously blown electrolytic cap and, voila, it came to life. As the box is completely potted it is really difficult to see anything on the circuit board.

When the charge enable is open cct, it blinks RRGG----. When the Enable is shorted it blinks RGRGRGRGRG then R-R-R-R...
Thanks,
Paul

Just to be certain we are talking about the same unit, my charger is the Elcon 3.3kW UHF charger (solid Al box with a fan on it).

Ah. I assumed a 3 kW older model, which is really two 1500 W charger units in one box. That ".3" is really important!

I'm only familiar with the older models. It seems that these old models are still available from Elcon USA, manufactured by TC Charger in China. I assumed that you had one of these. The newer models have a different processor, and starting with the 3.3 kW and 1.8 kW models, they have a radically different circuit. I suspect that these modern smaller models use wide band-gap devices, which allow greater efficiency and smaller size.

It is full of white potting. ... I am quite certain that the BMS has not told the Charger to stop. I even took it out of the picture and simply shorted the charger "Enable" wires together. Same result...20 Ah...stop (20 Ah is 1 hour at 20 A).

Ok, that settles it. Strange behaviour.

I've not heard any good stories from the new models. I don't know if that's because many people use them and they mostly just work as advertised, or if few people have tried them, or something else.

As I am a tinkerer, before I dropped it in the bin I took the lid off and dug around the potting where it was black from an obvious "smoke escape" event. I replaced an obviously blown electrolytic cap and, voila, it came to life.

Wow Well done.

When the charge enable is open cct, it blinks RRGG----. When the Enable is shorted it blinks RGRGRGRGRG then R-R-R-R...

It looks like flashing red is similar in meaning to that of the older models (bulk charging), but the RRGG---- code must be new. They really did need a different code for "no enable" as opposed to "I see no battery here".

Sorry, I have no further ideas about what is causing the charger to stop after an hour.

[ Edit: Added "these modern smaller models ". ]

Learning how to patch and repair PIP-4048 inverter-chargers and Elcon chargers.